Time to mount the drum and motor to the frame. The choice of 2 x 6 sides was made to hopefully eliminate any flexing when work pieces were in contact with the sanding surface. However, that lead to difficulty in figuring out how to be able to mount the drum bearings to the sides. Long carriage bolts can be expensive!
The sides are counter bored about 3” and then drilled to match the bolt diameter. An area around the mounting surface was mortised for an aluminum plate. The pillow block bearings will set on the plate, not the wooden surface. Again, my hope is to improve stability.
(counter bore and carriage bolts)
I was afraid that the soft pine might crush enough to allow the bolts to spin during tightening. Once everything was dry fitted, the bolt heads were Gorilla Glued to help prevent them from spinning.
Finally, the aluminum plates are placed in position- ready for the drum to be bolted down.
The motor is mounted to a piece of 3/4 “ plywood. The plywood is fastened to the frame using small “barn style” hinges at one end of the plywood. The weight of the motor creates the tension on the belt/pulley system. I routed slots for the motor mounting bolts in order to be able to adjust the motor side to side to align the belt/pulley.
(motor mount 1,2,3)